1. Field of the Invention
The present invention relates to an electron emission device and an electron emission display using the electron emission device, and in particular, to an electron emission device that improves an arrangement of electron emission regions and gate electrode opening portions for respective unit pixels, thereby increasing the electron emission efficiency.
2. Description of Related Art
In general, an electron emission element can be classified, depending upon the kinds of electron sources, into a hot cathode type or a cold cathode type.
Among the cold cathode type of electron emission elements, there are a field emitter array (FEA) type, a surface conduction emission (SCE) type, a metal-insulator-metal (MIM) type, and a metal-insulator-semiconductor (MIS) type.
The FEA type of electron emission element includes electron emission regions, and cathode and gate electrodes that are used as the driving electrodes for controlling the emission of electrons from the electron emission regions. The electron emission regions are formed with a material having a low work function and/or a high aspect ratio. For instance, the electron emission regions are formed with a carbonaceous material such as carbon nanotubes (CNT), graphite, and diamond-like carbon (DLC). With the usage of such a material for the electron emission regions, when an electric field is applied to the electron emission regions under a vacuum atmosphere (or vacuum state), electrons are easily emitted from these electron emission regions.
Arrays of the electron emission elements are arranged on a first substrate to form an electron emission device. A light emission unit is formed on a second substrate with phosphor layers and an anode electrode, which is assembled with the first substrate, thereby forming an electron emission display.
That is, the electron emission device includes the electron emission regions, and the plurality of driving electrodes functioning as the scan and data electrodes, which are operated to control the on/off and amount of electron emission for the respective unit pixels. With the electron emission display, the electrons emitted from the electron emission regions excite the phosphor layers, thereby emitting light or displaying the desired images.
With the typical FEA type of electron emission device, cathode electrodes, an insulating layer, and gate electrodes are sequentially formed on a substrate, and opening portions are formed at the gate electrode and the insulating layer to partially expose a surface of the cathode electrode. Electron emission regions are formed on the cathode electrode internal to the opening portion. Also, it is typical to serially arrange the electron emission regions along the longitudinal direction of the cathode electrodes for the respective unit pixels (or pixel units).
With the above structure, as the number of electron emission regions for the respective unit pixels is increased, the electron emission uniformity is enhanced, and the driving voltage is lowered. However, with the structure where the opening portions of the insulating layer and the gate electrode surround the respective electron emission regions, it is considerably more difficult in process (or manufacturing process) to increase the number of electron emission regions because the size of gate electrode opening portions needs to be reduced and/or the distance between the electron emission regions needs to be shortened.
Furthermore, with the above-structured electron emission device, electron fields are formed around the electron emission regions due to the voltage difference between the cathode and gate electrodes, and electrons are emitted from the electron emission regions due to the electric fields. As the electron emission regions and the gate electrodes are spaced apart from each other along a direction (or surface direction) of the first substrate, some electrons are emitted from the electron emission regions with a slant (or in a slanted manner), and are spread (or diffused) toward a counter substrate.
Consequently, the electrons collide with the phosphor layers at the relevant pixels as well as on the phosphor layers at other pixels neighboring thereto, thereby inducing incorrect color light emission and deteriorating the display quality. As such, there is a need to develop a structure that reduces or prevents the spreading of electron beams.